The present invention is related generally to primary electrochemical cells and is more particularly concerned with a novel preformed cathode for use in such cells and a method for its formation.
Primary electrochemical cells are utilized for a wide variety of applications and are commonly available in a significant assortment of sizes and shapes. Furthermore, a number of electrochemical systems are known for incorporation into such primary electrochemical cells. A large portion of these systems utilize a carbon cathode material. Typically, the carbon cathode material is formed as a paste and deposited as such within the electrochemical cell container. Because of the fluid form of this paste, albeit viscous, it is necessary to place a heavy separator between the carbon cathode material and the particular anode material utilized. This separator is required in order to prevent electrical contact between the anode and cathode materials. Necessarily, these separators become quite thick in order to prevent self-discharge of the cells due to internal shorts between the cathode and anode materials. Such a thick separator material naturally increases the internal resistance of the cell thereby decreasing the output which may be derived therefrom.
Preformed porous carbon cathodes have been developed which have significant advantages over previously known cathodes. However, cathodes of this general type have not been readily amenable to manufacture on high speed automated equipment. In the manufacturing process the desired thickness of cathode is sliced from a cathode bar by a reciprocating blade. Due to the inherent nature of the material additional labor steps are involved to suitably place the sponge cathode material into the cell container.